At the First Medical Clinic (First Medical Faculty, Charles University) a new method of assessment of impedance of hepatic tissue was developed. A special thin injection electrode was designed which makes it possible to take readings in deep tissue. The measurements are made and aimed throughout the procedure under ultrasonographic control. From the sites of assessment specimens were taken for cytological and histological examination. So far 44 operations were completed. In 33 patients according to ultrasonography focal changes were involved, in the remainder the liver parenchyma was homogeneous or there were slight diffuse changes. Based on the results of the histological examination, the group was divided into 11 subgroups some of which are very small and thus difficult to interpret. Therefore this is only a preliminary study. Its objective is to introduce the technique of a new method because even from the small hitherto assessed values of impedance by means of the injection electrode under ultrasonographic control the conclusion can be drawn that the assessed impedance values could provide more detailed information on the character of focal changes.